Imaging

GMOS can perform broad band imaging (using the SDSS filter system) or narrow-band imaging using selected filters. The field of view is 5.5 arcmin x 5.5 arcmin (and does not cover the entire CCD package).

Between the GMOS-S original EEV CCDs, GMOS-N original EEV CCDs, and upgraded GMOS-N e2v DD devices there are two ~ 2.8 arcsec (39 pixel) gaps, as shown in the image below. To cover the gaps it is recommended to use dither steps of at least 5 arcsec in the X-direction.

On the new Hamamatsu CCDs at GMOS-S the two gaps are 4.88 arcsec wide (61 pixels in unbinned mode). In this case it is recommended to use dither steps of 10 arcsec in the X-direction to cover the gaps.

The size of the gaps in the upgraded GMOS-N Hamamatsu detector package is expected to be similar, and will be determined when the CCDs are commissioned. See the Status and Availability webpage for more details.